Calorifiers – domestic hot water systemsCalorifiers or water heaters from Flexiheat UK

What are calorifiers?

Calorifiers are indirect-fired water heaters used in a heating and hot water system to provide domestic hot water. The term “indirect fired” refers to a water heater that does not have its own burner. It is a water storage cylinder with one or more heat exchanger coils containing hot liquids , normally water but can also be a solar fluid , or can be a tank in tank design of indirect hot water heaters.

The calorifier tank is designed to be connected to an external heat source, such as a gas boiler, an oil boiler, or a renewable energy system such as a heat pump, wood or pellet boiler, or an electric boiler.

The term calorifiers is used in the heating industry, and this is the area we are referring to. The term calorifiers is also used in the marine industry – a marine calorifier is a completely different to heating calorifiers as they are fed by engine coolant, that use drop coil technology.

External heat source

Generally, in the past calorifiers have been powered by a boiler heating water up to a temperature of normally 80C – this hot water is classified as the primary hot water which feeds a single coil normally fitted in lower half space or multiple coils (twin coil), within the water heaters tank.

Hot water calorifier showing the internal coil Flexiheat UK

Single coil shown inside the water heaters

The heat exchanger coils of the calorifier work by heating up the cold water in hot water cylinder to the required demand

The cold water contained in the water heater is then heated up to 60C to prevent the formation of legionella in the domestic hot water systems – this is known as the domestic hot water (commonly abbreviated to DHW)

Please note – You will require a calorifier with stainless coils if you have a central heating system with an aluminium heat exchanger or if there is any aluminium in the system. Galvanic corrosion, particularly the interaction of two dissimilar metals in water, will cause the calorifiers early demise.

For calorifier sizing, please see our webpage – commercial calorifier sizing

Click here – For our 80 to 500 litre indirect stainless steel calorifier range

Or for our 200 litre to 6,000 Litre commercial indirect hot water heaters  –  click here for our Commercial hot water cylinders

or click here for our twin coil cylinders range

and here for our tank in tank water heaters – which are high recovery water heaters

Electric heater backup or top up

Calorifiers can also have a backup or top up system for heating water, in the form of an immersion heater.

The immersion heater is powered by electricity, and in the case of heating boiler failure or when heat pumps can’t heat the water heaters to the desired temperature (normally the maximum is 55C that a heat pump can produce – remember we require at least 60C) then they, by efficient means (electric has 100% efficiency) , either replaces the function of the heating coil to heat the potable hot water directly or additionally to the heat generated by the coil in the case of heat pump’s, tops up the hot water heating demand.

Hot Water

Commercial buildings, leisure industry, sports facilities and public buildings domestic hot water systems are fed by water heater calorifiers normally on a DHW secondary return system to ensure the hot water system is heated and maintained above the temperature required to prevent the risk of legionella’s disease.

This guarantees that hot water is always accessible at any of the taps, regardless of their proximity to the calorifiers.

Hot water cylinder temperature control

All calorifiers require a thermostat to control the operation of the heat source supplying the water heater.

Domestic hot water calorifier

If you require any further assistance, latest offers / cost of our calorifiers range, which are indirect hot water cylinders for heating and hot water , please contact us via our email contact form /page above or call our sales team direct on 01202 822221.